Optical detection systems typically employ an image sensor having an array of photodetectors to detect incident light and then use information derived from the detected light for various purposes. In one example application, a time-of-flight (TOF) distance measuring system uses an image sensor to detect a target object and uses information derived from the detection to calculate a distance between the target object and the optical detection system. The accuracy of the distance measurement in the TOF distance measuring system is dependent upon a number of factors such as, for example, a pixel density of the image sensor and the nature of the processing carried out upon the information provided by the image sensor.
In another example application, a digital camera uses an image sensor to detect light information associated with a target object and use the detected light information to generate an image of the target object. As is generally known, the quality of the generated image is largely dependent on the pixel density of the image sensor and the nature of the processing circuitry in the digital camera. Consequently, it is desirable in most applications, to use an image sensor having a high pixel density and to couple this image sensor to a sophisticated processing circuit that can process the large amount of information provided by the high pixel density.
Unfortunately, using an image sensor with a high pixel density can lead to an undesirably high level of power consumption in the image sensor as well as in the processing circuitry coupled to the image sensor. The power consumption issue has been traditionally addressed by either compromising on the size of the image sensor that is used, or by using various techniques to minimize the amount of processing carried out by the processing circuitry coupled to a high pixel density sensor.
Among the various techniques used to minimize the amount of processing carried out by the processing circuitry, one technique involves processing only a subset of pixel information obtained from the image sensor. Even if this approach were to provide certain advantages in terms of image processing, it can be appreciated that in terms of power consumption, the use a one-size-fits-all imaging sensor that consumes power while generating more pixel information than needed is generally undesirable.
It is therefore desirable to provide an optical detection system that addresses at least some of the issues associated with traditional optical detection systems.